Not applicable.
The present invention is directed to apparatus and methods for fueling fuel tanks with compressed fuel. In particular, the present invention is directed to the grounding of an operator during the compressed fuel fueling process.
Fueling the fuel tanks of vehicles and other mobile apparatus with gaseous fuels such as hydrogen or compressed natural gas can be accomplished rapidly by discharging the fuel from high pressure storage vessels into, for example, the fuel tank or storage vessel in the vehicle or other mobile apparatus requiring fuel. It is imperative that the fuel be delivered safely to the vehicle. The point of the fueling process that may pose a potential hazard occurs when the operator disconnects the fuel fill nozzle from the vehicle. The operator may have built up static charge upon his or her person. If there is a leak of fuel from the station or vehicle, then, as the operator tries to remove the nozzle, a spark from a static discharge may ignite the gaseous fuel.
This may also be a hazard with liquid fuels. However, to date, the industry has not adequately addressed the problem. This may change since there were more than forty reports of gasoline fires due to operator static in the combined years of 1999 and 2000.
In the past, there have been a limited number of known attempts to directly address fueling of vehicles with compressed gas and the problem of potential fires due to static discharge. For example, in U.S. Pat. No. 5,029,622 (Mutter), an automated process for filling a vehicle with a compressed gas is described. However, there is no disclosure related to reducing or eliminating the problem of static discharge from the operator during the fuel filling operation.
It is known that vehicle static discharge may be avoided by use of a conductive fuel hose. This may be done for both gasoline as well as natural gas vehicles pursuant to National Fire Protection Association Code NFPA 77 xe2x80x9cRecommended Practice on Static Electricity.xe2x80x9d Section 4-5.3.6. of NFPA 77 states xe2x80x9call metallic parts of the fill pipe assembly should form a continuous electrically conductive path downstream from the point of bonding. For example, insertion of a nonconductive hose equipped with a metal coupling on the outlet must be avoided unless the coupling is bonded to the fill pipe.xe2x80x9d
In Von Pidoll et. al. xe2x80x9cAvoidance of Electrostatic Hazards During Refueling of Motorcars,xe2x80x9d Journal of Electrostatics, 40 and41, 1997, pages 523-528, the authors note that there were more than 30 ignitions of gasoline/air mixtures at public filling stations in Germany in a particular time period. One of their recommendations is the use of antistatic seats in all cars. This suggestion has not been accepted for gasoline cars to date, and it does not seem that this recommendation will be accepted for alternative fuels in the near future. This suggestion also does not protect the operator from other sources of static buildup such as their clothes.
In Kassebaum and Kocken, xe2x80x9cControlling Static Electricity in Hazardous (Classified) Locations,xe2x80x9d IEEE Trans. On Indus. Applics., Vol. 33, No. 1, January/February 1997, the authors recommend the use of conductive soled shoes for certain areas where there is potential for fire due to presence of flammable liquids, gases and dusts. A fueling station for the fueling of, for example, hydrogen gas, as used in the present invention, can be considered such an area where conductive soled shoes might be recommended. However, it cannot be expected that customers of fueling stations for hydrogen fuel for, for example, a fuel cell powered vehicle, have the correct footwear if such hydrogen fuel stations are going to be widely commercialized.
It is principally desired to provide a safety system and method for grounding an operator at a fueling station prior to removing a fuel fill nozzle from a fuel tank upon completion of a fuel filling operation.
It is further desired to provide a safety system and method for grounding an operator at a fueling station prior to removing a fuel fill nozzle from a fuel tank upon completion of a fuel filling operation that is simple and relatively inexpensive.
It is still further desired to provide a safety system and method for grounding an operator at a fueling station prior to removing a fuel fill nozzle from a fuel tank upon completion of a fuel filling operation that is not prone to operator error.
Finally, it is desired to provide a safety system and method for grounding an operator at a fueling station prior to removing a fuel fill nozzle from a fuel tank upon completion of a fuel filling operation that is specifically for use for hydrogen in fuel cell tanks, but may also be used with respect to filling other fuel tanks with flammable fuels.
The present invention is directed to the grounding of such an operator subsequent to the filling operation and prior to removal of the fuel fill nozzle. In the present invention, the operator is either notified that he must ground himself prior to removal of the nozzle, or the nozzle itself is locked into the vehicle port. Automatic nozzles that lock and unlock to a vehicle port have been built for natural gas vehicle (NGV) service, for example, the WEH GmbH of Germany, nozzle type WEH TK 18, but none is locked or unlocked by action of grounding.
While the present invention addresses grounding of an operator while filling a fuel cell tank with hydrogen, all embodiments of the present invention apply equally well to filling a fuel tank with a flammable gas or flammable liquid that emits flammable vapors, such as gasoline. It is believed that the present invention is the first attempt to solve the problem of potential static discharge at the end of a vehicle fill process by the grounding of the fuel fill operator.
The first embodiment of the present invention is directed to a safety system for grounding an operator at a fueling station prior to removing a fuel fill nozzle from a fuel tank upon completion of a fuel filling operation. The safety system includes a fuel tank port in communication with the fuel tank for receiving and retaining the fuel fill nozzle during the fuel filling operation. The safety system further includes a grounding device adjacent to the fuel tank port which includes a grounding switch having a contact member that receives physical contact by the operator. Physical contact of the contact member by the operator activates the grounding switch. A releasable interlock is also included that provides a lock position wherein the nozzle is locked into the port upon insertion of the nozzle into the port and a release position wherein the nozzle is releasable from the port upon completion of the fuel filling operation and after physical contact of the contact member is accomplished. Accidental ignition of fuel due to static discharge is thereby prevented.
Preferably, the grounding device is located at least two centimeters from the nozzle. Additionally, it is preferable that the fuel source contain a compressed fuel and the fuel is hydrogen.
The releasable interlock may be a manually activated nozzle lever, wherein movement of the nozzle lever in a first direction locks the nozzle to the fuel tank port and wherein movement of the nozzle lever in a second direction unlocks the nozzle from the fuel tank port only upon activation of the grounding switch. Preferably, the first direction and the second direction are opposed, i.e., are directed 180 degrees from one another. For example, the first direction may be toward the left and the second direction may be toward the right, although such feature is not essential or required. Many combinations of first and second directions can be engineered without undue experimentation.
A timer may be included that is connected to the releasable interlock where the timer provides for the releasable interlock to remain in the release position for a limited time period subsequent to activation of the grounding switch. The timer provides for the releasable interlock to remain in the locked position at all other times when the nozzle is received in the port. The limited time period may be about one to three hundred seconds and preferably about five seconds.
An indicator to provide indication that the nozzle may safely be removed from the receptacle may be provided where the indicator provides indication during the limited time period.
The grounding switch may be integral to the releasable interlock. The releasable interlock may be a lever that moves from the lock position to the release position, whereby the lever blocks the nozzle from removal from the fuel tank port until moved from the lock position to the release position. A grounding verification switch adjacent to the nozzle and a timer connected to the releasable interlock may also be provided. The grounding verification switch is connected to a fuel controller where the fuel controller enables flow of the fuel from the nozzle only during activation of the grounding verification switch and the timer provides for the releasable interlock to remain in the release position for a limited time period subsequent to release of the grounding verification switch. The grounding verification switch may include an activation handle on the nozzle that controls flow of fuel.
A grounding verification switch may be included along with a timer. The grounding verification switch connects to the fuel controller, the fuel controller enabling flow of the fuel from the nozzle only during activation of the grounding verification switch. The timer is connected to the fuel controller and provides for flow of fuel to resume once halted by release of the grounding verification switch for a limited time period subsequent to release of the grounding verification switch. The fuel controller provides for no fuel to flow after the limited time period has been reached until the grounding switch is re-activated.
Another embodiment of a safety system for grounding an operator at a fueling station during a fuel filling operation is also provided which includes a fuel tank port in communication with a fuel tank for receiving a fuel fill nozzle, a grounding device adjacent to the fuel tank port, the grounding device including a grounding switch having a contact member to receive physical contact by the operator. Physical contact of the contact member activates the grounding switch. A fuel controller is provided for providing fuel flow through the nozzle only when the grounding switch is continuously activated.
Another embodiment of a safety system for grounding an operator at a fueling station during a fuel filling operation is also provided which includes a fuel tank port in communication with a fuel tank for receiving a fuel fill nozzle, a grounding device adjacent to the fuel tank port, the grounding device including a contact member connected to ground which is adapted to receive physical contact by the operator, and a fuel controller for controlling fuel flow through the nozzle. The fuel controller provides for a flow of fuel, and provides a signal when the controller provides for fuel to stop flowing. An indicator is also provided that indicates to the operator, immediately upon receiving the signal, that grounding must take place prior to removal of the nozzle.
A method for grounding an operator at a fueling station is also provided which includes the steps of providing the apparatus of the first embodiment, withdrawing the fuel fill nozzle from a fuel source boot, inserting the fuel fill nozzle into the fuel tank port whereby the nozzle is locked into the fuel tank port, filling the fuel tank with fuel from a fuel source, contacting the contact member to activate the grounding switch of the grounding member to release the releasable interlock, and withdrawing the nozzle from the port. The operator may also have to contact a grounding verification switch that is connected to ground during the activation process. The operator may have a limited time period in which he or she must remove the nozzle from the port after the fueling and grounding process is complete.
Another method for grounding an operator at a fueling station during a fuel filling operation is also provided which includes providing a fuel tank port in communication with a fuel tank for receiving a fuel fill nozzle during the fuel filling operation. A grounding device adjacent to the fuel tank port is provided wherein the grounding device includes a grounding switch having a contact member to receive physical contact by the operator, wherein physical contact of the contact member activates the grounding switch. A fuel controller is provided that is activatable by the grounding switch to provide fuel flow through the nozzle only when the grounding switch is continuously activated. The contact member is physically contacted to activate the grounding switch which activates the fuel controller to provide fuel flow.
Finally, in another embodiment of the present invention, a method for grounding an operator at a fueling station during a fuel filling operation is provided which includes providing a fuel fill nozzle connected to a fuel source, providing a fuel tank port in communication with a fuel tank for receiving the fuel fill nozzle, and providing a grounding device adjacent to the fuel tank port, the grounding device including a contact member connected to ground which is adapted to receive physical contact by the operator. A fuel controller for controlling fuel flow through the nozzle is also provided where the fuel controller provides a signal when the controller provides fuel to stop flowing. An indicator is provided that indicates to the operator, immediately upon receiving the signal, that grounding must take place prior to removal of the nozzle. The nozzle is inserted into the fuel tank port, a desired quantity of fuel is input into the fuel tank via the fuel controller until the desired quantity of fuel has been transferred or the fuel tank has reached capacity. The signal from the controller to the indicator is provided to indicate to the operator that the operator must contact the contact member. The operator contacts the contact member and the nozzle is removed from the fuel tank port.